NUDT15 R139C-Related Thiopurine Leukocytopenia Is Mediated by 6-Thioguanine Nucleotide-Independent Mechanism in Japanese Patients with Inflammatory Bowel Disease

The study concluded that the NUDT15 R139C variant caused thiopurine-induced leukocytopenia through a mechanism independent of 6-thioguanine nucleotide levels in Japanese patients with inflammatory bowel disease. This finding suggested that the adverse effects of thiopurine drugs in these patients were not solely due to the accumulation of 6-thioguanine nucleotides, indicating the need for alternative monitoring and management strategies for those carrying the NUDT15 R139C variant.